package dujiu.luogu.circulation;

import java.util.Scanner;

public class P1423 {
    public static void main(String[] args) {
        Scanner scanner = new Scanner(System.in);
        // 需要游的目标距离
        double s = scanner.nextDouble();
        scanner.close();

        double start = 2.0;
        double sum = 0.0;
        int count = 0;
        while (sum < s){
            sum += start;
            count++;
            start *= 0.98;
        }
        System.out.println(count);
    }
}
